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  • Much Ado About Nothing: Stub Objects

    - by user9154181
    The Solaris 11 link-editor (ld) contains support for a new type of object that we call a stub object. A stub object is a shared object, built entirely from mapfiles, that supplies the same linking interface as the real object, while containing no code or data. Stub objects cannot be executed — the runtime linker will kill any process that attempts to load one. However, you can link to a stub object as a dependency, allowing the stub to act as a proxy for the real version of the object. You may well wonder if there is a point to producing an object that contains nothing but linking interface. As it turns out, stub objects are very useful for building large bodies of code such as Solaris. In the last year, we've had considerable success in applying them to one of our oldest and thorniest build problems. In this discussion, I will describe how we came to invent these objects, and how we apply them to building Solaris. This posting explains where the idea for stub objects came from, and details our long and twisty journey from hallway idea to standard link-editor feature. I expect that these details are mainly of interest to those who work on Solaris and its makefiles, those who have done so in the past, and those who work with other similar bodies of code. A subsequent posting will omit the history and background details, and instead discuss how to build and use stub objects. If you are mainly interested in what stub objects are, and don't care about the underlying software war stories, I encourage you to skip ahead. The Long Road To Stubs This all started for me with an email discussion in May of 2008, regarding a change request that was filed in 2002, entitled: 4631488 lib/Makefile is too patient: .WAITs should be reduced This CR encapsulates a number of cronic issues with Solaris builds: We build Solaris with a parallel make (dmake) that tries to build as much of the code base in parallel as possible. There is a lot of code to build, and we've long made use of parallelized builds to get the job done quicker. This is even more important in today's world of massively multicore hardware. Solaris contains a large number of executables and shared objects. Executables depend on shared objects, and shared objects can depend on each other. Before you can build an object, you need to ensure that the objects it needs have been built. This implies a need for serialization, which is in direct opposition to the desire to build everying in parallel. To accurately build objects in the right order requires an accurate set of make rules defining the things that depend on each other. This sounds simple, but the reality is quite complex. In practice, having programmers explicitly specify these dependencies is a losing strategy: It's really hard to get right. It's really easy to get it wrong and never know it because things build anyway. Even if you get it right, it won't stay that way, because dependencies between objects can change over time, and make cannot help you detect such drifing. You won't know that you got it wrong until the builds break. That can be a long time after the change that triggered the breakage happened, making it hard to connect the cause and the effect. Usually this happens just before a release, when the pressure is on, its hard to think calmly, and there is no time for deep fixes. As a poor compromise, the libraries in core Solaris were built using a set of grossly incomplete hand written rules, supplemented with a number of dmake .WAIT directives used to group the libraries into sets of non-interacting groups that can be built in parallel because we think they don't depend on each other. From time to time, someone will suggest that we could analyze the built objects themselves to determine their dependencies and then generate make rules based on those relationships. This is possible, but but there are complications that limit the usefulness of that approach: To analyze an object, you have to build it first. This is a classic chicken and egg scenario. You could analyze the results of a previous build, but then you're not necessarily going to get accurate rules for the current code. It should be possible to build the code without having a built workspace available. The analysis will take time, and remember that we're constantly trying to make builds faster, not slower. By definition, such an approach will always be approximate, and therefore only incremantally more accurate than the hand written rules described above. The hand written rules are fast and cheap, while this idea is slow and complex, so we stayed with the hand written approach. Solaris was built that way, essentially forever, because these are genuinely difficult problems that had no easy answer. The makefiles were full of build races in which the right outcomes happened reliably for years until a new machine or a change in build server workload upset the accidental balance of things. After figuring out what had happened, you'd mutter "How did that ever work?", add another incomplete and soon to be inaccurate make dependency rule to the system, and move on. This was not a satisfying solution, as we tend to be perfectionists in the Solaris group, but we didn't have a better answer. It worked well enough, approximately. And so it went for years. We needed a different approach — a new idea to cut the Gordian Knot. In that discussion from May 2008, my fellow linker-alien Rod Evans had the initial spark that lead us to a game changing series of realizations: The link-editor is used to link objects together, but it only uses the ELF metadata in the object, consisting of symbol tables, ELF versioning sections, and similar data. Notably, it does not look at, or understand, the machine code that makes an object useful at runtime. If you had an object that only contained the ELF metadata for a dependency, but not the code or data, the link-editor would find it equally useful for linking, and would never know the difference. Call it a stub object. In the core Solaris OS, we require all objects to be built with a link-editor mapfile that describes all of its publically available functions and data. Could we build a stub object using the mapfile for the real object? It ought to be very fast to build stub objects, as there are no input objects to process. Unlike the real object, stub objects would not actually require any dependencies, and so, all of the stubs for the entire system could be built in parallel. When building the real objects, one could link against the stub objects instead of the real dependencies. This means that all the real objects can be built built in parallel too, without any serialization. We could replace a system that requires perfect makefile rules with a system that requires no ordering rules whatsoever. The results would be considerably more robust. We immediately realized that this idea had potential, but also that there were many details to sort out, lots of work to do, and that perhaps it wouldn't really pan out. As is often the case, it would be necessary to do the work and see how it turned out. Following that conversation, I set about trying to build a stub object. We determined that a faithful stub has to do the following: Present the same set of global symbols, with the same ELF versioning, as the real object. Functions are simple — it suffices to have a symbol of the right type, possibly, but not necessarily, referencing a null function in its text segment. Copy relocations make data more complicated to stub. The possibility of a copy relocation means that when you create a stub, the data symbols must have the actual size of the real data. Any error in this will go uncaught at link time, and will cause tragic failures at runtime that are very hard to diagnose. For reasons too obscure to go into here, involving tentative symbols, it is also important that the data reside in bss, or not, matching its placement in the real object. If the real object has more than one symbol pointing at the same data item, we call these aliased symbols. All data symbols in the stub object must exhibit the same aliasing as the real object. We imagined the stub library feature working as follows: A command line option to ld tells it to produce a stub rather than a real object. In this mode, only mapfiles are examined, and any object or shared libraries on the command line are are ignored. The extra information needed (function or data, size, and bss details) would be added to the mapfile. When building the real object instead of the stub, the extra information for building stubs would be validated against the resulting object to ensure that they match. In exploring these ideas, I immediately run headfirst into the reality of the original mapfile syntax, a subject that I would later write about as The Problem(s) With Solaris SVR4 Link-Editor Mapfiles. The idea of extending that poor language was a non-starter. Until a better mapfile syntax became available, which seemed unlikely in 2008, the solution could not involve extentions to the mapfile syntax. Instead, we cooked up the idea (hack) of augmenting mapfiles with stylized comments that would carry the necessary information. A typical definition might look like: # DATA(i386) __iob 0x3c0 # DATA(amd64,sparcv9) __iob 0xa00 # DATA(sparc) __iob 0x140 iob; A further problem then became clear: If we can't extend the mapfile syntax, then there's no good way to extend ld with an option to produce stub objects, and to validate them against the real objects. The idea of having ld read comments in a mapfile and parse them for content is an unacceptable hack. The entire point of comments is that they are strictly for the human reader, and explicitly ignored by the tool. Taking all of these speed bumps into account, I made a new plan: A perl script reads the mapfiles, generates some small C glue code to produce empty functions and data definitions, compiles and links the stub object from the generated glue code, and then deletes the generated glue code. Another perl script used after both objects have been built, to compare the real and stub objects, using data from elfdump, and validate that they present the same linking interface. By June 2008, I had written the above, and generated a stub object for libc. It was a useful prototype process to go through, and it allowed me to explore the ideas at a deep level. Ultimately though, the result was unsatisfactory as a basis for real product. There were so many issues: The use of stylized comments were fine for a prototype, but not close to professional enough for shipping product. The idea of having to document and support it was a large concern. The ideal solution for stub objects really does involve having the link-editor accept the same arguments used to build the real object, augmented with a single extra command line option. Any other solution, such as our prototype script, will require makefiles to be modified in deeper ways to support building stubs, and so, will raise barriers to converting existing code. A validation script that rederives what the linker knew when it built an object will always be at a disadvantage relative to the actual linker that did the work. A stub object should be identifyable as such. In the prototype, there was no tag or other metadata that would let you know that they weren't real objects. Being able to identify a stub object in this way means that the file command can tell you what it is, and that the runtime linker can refuse to try and run a program that loads one. At that point, we needed to apply this prototype to building Solaris. As you might imagine, the task of modifying all the makefiles in the core Solaris code base in order to do this is a massive task, and not something you'd enter into lightly. The quality of the prototype just wasn't good enough to justify that sort of time commitment, so I tabled the project, putting it on my list of long term things to think about, and moved on to other work. It would sit there for a couple of years. Semi-coincidentally, one of the projects I tacked after that was to create a new mapfile syntax for the Solaris link-editor. We had wanted to do something about the old mapfile syntax for many years. Others before me had done some paper designs, and a great deal of thought had already gone into the features it should, and should not have, but for various reasons things had never moved beyond the idea stage. When I joined Sun in late 2005, I got involved in reviewing those things and thinking about the problem. Now in 2008, fresh from relearning for the Nth time why the old mapfile syntax was a huge impediment to linker progress, it seemed like the right time to tackle the mapfile issue. Paving the way for proper stub object support was not the driving force behind that effort, but I certainly had them in mind as I moved forward. The new mapfile syntax, which we call version 2, integrated into Nevada build snv_135 in in February 2010: 6916788 ld version 2 mapfile syntax PSARC/2009/688 Human readable and extensible ld mapfile syntax In order to prove that the new mapfile syntax was adequate for general purpose use, I had also done an overhaul of the ON consolidation to convert all mapfiles to use the new syntax, and put checks in place that would ensure that no use of the old syntax would creep back in. That work went back into snv_144 in June 2010: 6916796 OSnet mapfiles should use version 2 link-editor syntax That was a big putback, modifying 517 files, adding 18 new files, and removing 110 old ones. I would have done this putback anyway, as the work was already done, and the benefits of human readable syntax are obvious. However, among the justifications listed in CR 6916796 was this We anticipate adding additional features to the new mapfile language that will be applicable to ON, and which will require all sharable object mapfiles to use the new syntax. I never explained what those additional features were, and no one asked. It was premature to say so, but this was a reference to stub objects. By that point, I had already put together a working prototype link-editor with the necessary support for stub objects. I was pleased to find that building stubs was indeed very fast. On my desktop system (Ultra 24), an amd64 stub for libc can can be built in a fraction of a second: % ptime ld -64 -z stub -o stubs/libc.so.1 -G -hlibc.so.1 \ -ztext -zdefs -Bdirect ... real 0.019708910 user 0.010101680 sys 0.008528431 In order to go from prototype to integrated link-editor feature, I knew that I would need to prove that stub objects were valuable. And to do that, I knew that I'd have to switch the Solaris ON consolidation to use stub objects and evaluate the outcome. And in order to do that experiment, ON would first need to be converted to version 2 mapfiles. Sub-mission accomplished. Normally when you design a new feature, you can devise reasonably small tests to show it works, and then deploy it incrementally, letting it prove its value as it goes. The entire point of stub objects however was to demonstrate that they could be successfully applied to an extremely large and complex code base, and specifically to solve the Solaris build issues detailed above. There was no way to finesse the matter — in order to move ahead, I would have to successfully use stub objects to build the entire ON consolidation and demonstrate their value. In software, the need to boil the ocean can often be a warning sign that things are trending in the wrong direction. Conversely, sometimes progress demands that you build something large and new all at once. A big win, or a big loss — sometimes all you can do is try it and see what happens. And so, I spent some time staring at ON makefiles trying to get a handle on how things work, and how they'd have to change. It's a big and messy world, full of complex interactions, unspecified dependencies, special cases, and knowledge of arcane makefile features... ...and so, I backed away, put it down for a few months and did other work... ...until the fall, when I felt like it was time to stop thinking and pondering (some would say stalling) and get on with it. Without stubs, the following gives a simplified high level view of how Solaris is built: An initially empty directory known as the proto, and referenced via the ROOT makefile macro is established to receive the files that make up the Solaris distribution. A top level setup rule creates the proto area, and performs operations needed to initialize the workspace so that the main build operations can be launched, such as copying needed header files into the proto area. Parallel builds are launched to build the kernel (usr/src/uts), libraries (usr/src/lib), and commands. The install makefile target builds each item and delivers a copy to the proto area. All libraries and executables link against the objects previously installed in the proto, implying the need to synchronize the order in which things are built. Subsequent passes run lint, and do packaging. Given this structure, the additions to use stub objects are: A new second proto area is established, known as the stub proto and referenced via the STUBROOT makefile macro. The stub proto has the same structure as the real proto, but is used to hold stub objects. All files in the real proto are delivered as part of the Solaris product. In contrast, the stub proto is used to build the product, and then thrown away. A new target is added to library Makefiles called stub. This rule builds the stub objects. The ld command is designed so that you can build a stub object using the same ld command line you'd use to build the real object, with the addition of a single -z stub option. This means that the makefile rules for building the stub objects are very similar to those used to build the real objects, and many existing makefile definitions can be shared between them. A new target is added to the Makefiles called stubinstall which delivers the stub objects built by the stub rule into the stub proto. These rules reuse much of existing plumbing used by the existing install rule. The setup rule runs stubinstall over the entire lib subtree as part of its initialization. All libraries and executables link against the objects in the stub proto rather than the main proto, and can therefore be built in parallel without any synchronization. There was no small way to try this that would yield meaningful results. I would have to take a leap of faith and edit approximately 1850 makefiles and 300 mapfiles first, trusting that it would all work out. Once the editing was done, I'd type make and see what happened. This took about 6 weeks to do, and there were many dark days when I'd question the entire project, or struggle to understand some of the many twisted and complex situations I'd uncover in the makefiles. I even found a couple of new issues that required changes to the new stub object related code I'd added to ld. With a substantial amount of encouragement and help from some key people in the Solaris group, I eventually got the editing done and stub objects for the entire workspace built. I found that my desktop system could build all the stub objects in the workspace in roughly a minute. This was great news, as it meant that use of the feature is effectively free — no one was likely to notice or care about the cost of building them. After another week of typing make, fixing whatever failed, and doing it again, I succeeded in getting a complete build! The next step was to remove all of the make rules and .WAIT statements dedicated to controlling the order in which libraries under usr/src/lib are built. This came together pretty quickly, and after a few more speed bumps, I had a workspace that built cleanly and looked like something you might actually be able to integrate someday. This was a significant milestone, but there was still much left to do. I turned to doing full nightly builds. Every type of build (open, closed, OpenSolaris, export, domestic) had to be tried. Each type failed in a new and unique way, requiring some thinking and rework. As things came together, I became aware of things that could have been done better, simpler, or cleaner, and those things also required some rethinking, the seeking of wisdom from others, and some rework. After another couple of weeks, it was in close to final form. My focus turned towards the end game and integration. This was a huge workspace, and needed to go back soon, before changes in the gate would made merging increasingly difficult. At this point, I knew that the stub objects had greatly simplified the makefile logic and uncovered a number of race conditions, some of which had been there for years. I assumed that the builds were faster too, so I did some builds intended to quantify the speedup in build time that resulted from this approach. It had never occurred to me that there might not be one. And so, I was very surprised to find that the wall clock build times for a stock ON workspace were essentially identical to the times for my stub library enabled version! This is why it is important to always measure, and not just to assume. One can tell from first principles, based on all those removed dependency rules in the library makefile, that the stub object version of ON gives dmake considerably more opportunities to overlap library construction. Some hypothesis were proposed, and shot down: Could we have disabled dmakes parallel feature? No, a quick check showed things being build in parallel. It was suggested that we might be I/O bound, and so, the threads would be mostly idle. That's a plausible explanation, but system stats didn't really support it. Plus, the timing between the stub and non-stub cases were just too suspiciously identical. Are our machines already handling as much parallelism as they are capable of, and unable to exploit these additional opportunities? Once again, we didn't see the evidence to back this up. Eventually, a more plausible and obvious reason emerged: We build the libraries and commands (usr/src/lib, usr/src/cmd) in parallel with the kernel (usr/src/uts). The kernel is the long leg in that race, and so, wall clock measurements of build time are essentially showing how long it takes to build uts. Although it would have been nice to post a huge speedup immediately, we can take solace in knowing that stub objects simplify the makefiles and reduce the possibility of race conditions. The next step in reducing build time should be to find ways to reduce or overlap the uts part of the builds. When that leg of the build becomes shorter, then the increased parallelism in the libs and commands will pay additional dividends. Until then, we'll just have to settle for simpler and more robust. And so, I integrated the link-editor support for creating stub objects into snv_153 (November 2010) with 6993877 ld should produce stub objects PSARC/2010/397 ELF Stub Objects followed by the work to convert the ON consolidation in snv_161 (February 2011) with 7009826 OSnet should use stub objects 4631488 lib/Makefile is too patient: .WAITs should be reduced This was a huge putback, with 2108 modified files, 8 new files, and 2 removed files. Due to the size, I was allowed a window after snv_160 closed in which to do the putback. It went pretty smoothly for something this big, a few more preexisting race conditions would be discovered and addressed over the next few weeks, and things have been quiet since then. Conclusions and Looking Forward Solaris has been built with stub objects since February. The fact that developers no longer specify the order in which libraries are built has been a big success, and we've eliminated an entire class of build error. That's not to say that there are no build races left in the ON makefiles, but we've taken a substantial bite out of the problem while generally simplifying and improving things. The introduction of a stub proto area has also opened some interesting new possibilities for other build improvements. As this article has become quite long, and as those uses do not involve stub objects, I will defer that discussion to a future article.

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  • St. Louis ALT.NET

    - by Brian Schroer
    I’m a huge fan of the St. Louis .NET User Group and a regular attendee of their meetings, but always wished there was a local group that discussed more advanced .NET topics. (That’s not a criticism of the group - I appreciate that they want to server developers with a broad range of skill levels). That’s why I was thrilled when Nicholas Cloud started a St. Louis ALT.NET group in 2010. Here’s the “about us” statement from the group’s web site: The ALT.NET community is a loosely coupled, highly cohesive group of like-minded individuals who believe that the best developers do not align themselves with platforms and languages, but with principles and ideas. In 2007, David Laribee created the term "ALT.NET" to explain this "alternative" view of the Microsoft development universe--a view that challenged the "Microsoft-only" approach to software development. He distilled his thoughts into four key developer characteristics which form the basis of the ALT.NET philosophy: You're the type of developer who uses what works while keeping an eye out for a better way. You reach outside the mainstream to adopt the best of any community: Open Source, Agile, Java, Ruby, etc. You're not content with the status quo. Things can always be better expressed, more elegant and simple, more mutable, higher quality, etc. You know tools are great, but they only take you so far. It's the principles and knowledge that really matter. The best tools are those that embed the knowledge and encourage the principles (e.g. Resharper.) The St. Louis ALT.NET meetup group is a place where .NET developers can learn, share, and critique approaches to software development on the .NET stack. We cater to the highest common denominator, not the lowest, and want to help all St. Louis .NET developers achieve a superior level of software craftsmanship. I don’t see a lot of ALT.NET talk in blogs these days. The movement was harmed early on by the negative attitudes of some of its early leaders, including jerk moves like the Entity Framework “vote of no confidence”, but I do see occasional mentions of local groups like the St. Louis one. I think ALT.NET has been successful at bringing some of its ideas into the .NET world, including heavily influencing ASP.NET MVC and raising the general level of software craftsmanship for developers working on the Microsoft stack. The ideas and ideals live on, they’re just not branded as “this is ALT.NET!” In the past 18 months, St. Louis ALT.NET meetups have discussed topics like: NHibernate F# and other functional languages AOP CoffeeScript “How Ruby Is Making Me a Stronger C# Developer” Using rake for builds CQRS .NET dynamic programming micro web frameworks – Nancy & Jessica Git ALT.NET doesn’t mean (to me, anyway) “alternatives to .NET”, but “alternatives for .NET”. We look at how things are done in Ruby and other languages/platforms, but always with the idea “What can I learn from this to take back to my “day job” with .NET?”. Meetings are held at 7PM on the fourth Wednesday of each month at the offices of Professional Employment Group. PEG is located at 999 Executive Parkway (Suite 100 – lower level) in Creve Coeur (South of Olive off of Mason Road - Here's a map). Food is not supplied (sorry if you’re a big fan of the Papa John’s Crust-Lovers’ Pizza that’s a staple of user group meetings), but attendees are encouraged to come early and bring/share beer, so that’s cool. Thanks to Nick for organizing, and to Professional Employment Group for lending their offices. Please visit the meetup site for more information.

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  • Exposing business logic as WCF service

    - by Oren Schwartz
    I'm working on a middle-tier project which encapsulates the business logic (uses a DAL layer, and serves a web application server [ASP.net]) of a product deployed in a LAN. The BL serves as a bunch of services and data objects that are invoked upon user action. At present times, the DAL acts as a separate application whereas the BL uses it, but is consumed by the web application as a DLL. Both the DAL and the web application are deployed on different servers inside organization, and since the BL DLL is consumed by the web application, it resides in the same server. The worst thing about exposing the BL as a DLL is that we lost track with what we expose. Deployment is not such a big issue since mostly, product versions are deployed together. Would you recommend migrating from DLL to WCF service? If so, why? Do you know anyone who had a similar experience?

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  • Is it a good idea to put all assembly: WebResource in the same cs file?

    - by Guilherme J Santos
    I have a .NET library, with some WebControls. These webControls have Embed Resources. And we declare them like it, in all webcontrols for each cs file: Something like this: [assembly: WebResource("IO.Css.MyCSS.css", "text/css")] namespace MyNamespace.MyClass { [ParseChildren(true)] [PersistChildren(false)] [Designer(typeof(MyNamespace.MyClassDesigner))] public class QuickTip : Control, INamingContainer { //My code... } } Would it be a good idea to create a cs file and include all WebResource declarations there? Example a cs file with just: [assembly: WebResource("IO.Css.MyCSS.css", "text/css")] [assembly: WebResource("IO.Image.MyImage.png", "image/png")] //And many other WebResources of all WebControls of the Assembly

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  • ASP.NET MVC Resource not found

    - by TheLorax
    I am working on an MVC project in Visual Studio 2010 with .NET Framework 4.0 + MVC2 and everything works if I set the target framework to .NET 4.0. However, my host does not offer .NET 4.0 in order to deploy the site I need to get it working on .NET 3.5. I tried converting it to ASP.NET 3.5 and everything builds just fine except now when I try to load the homepage, I get a 404 Error saying: The resource cannot be found. Description: HTTP 404. The resource you are looking for (or one of its dependencies) could have been removed, had its name changed, or is temporarily unavailable. Please review the following URL and make sure that it is spelled correctly. Requested URL: /home Version Information: Microsoft .NET Framework Version:2.0.50727.4927; ASP.NET Version:2.0.50727.4927 Anyone know why this is? Thank You for Your help. TheLorax

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  • Why should I use List<T> over IEnumerable<T>?

    - by Rowan Freeman
    In my ASP.net MVC4 web application I use IEnumerables, trying to follow the mantra to program to the interface, not the implementation. Return IEnumerable(Of Student) vs Return New List(Of Student) People are telling me to use List and not IEnumerable, because lists force the query to be executed and IEumerable does not. Is this really best practice? Is there any alternative? I feel strange using concrete objects where an interface could be used. Is my strange feeling justified?

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  • Build an ASP.NET 3.5 Guestbook using MS SQL Server and VB.NET

    One of the most important website features is a guest book. This is particularly useful if you need to know the responses and reactions of your website s visitors. With the release of ASP.NET 3.5 and Visual Web Developer Express 2 8 several web controls make it possible to create an ASP.NET application without the need to hard manually code everything including database scripts server side scripts etc. You can see how that would be helpful to writing a guest book. This is the first part of a multi-part series.... SW Deployment Automation Best Practices Free Guide for IT Leaders: Overcoming Software Distribution & Mgmt Challenges.

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  • Much ado about NULL: Exploiting a kernel NULL dereference

    <b>Ksplice:</b> "We think that it&#8217;s important for developers and system administrators to be more knowledgeable about the attacks that black hats regularly use to take control of systems, and so, today, we&#8217;re going to start from where we left off and go all the way to a working exploit for a NULL pointer dereference in a toy kernel module."

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  • .Net Application & Database Modularity/Reuse

    - by Martaver
    I'm looking for some guidance on how to architect an app with regards to modularity, separation of concerns and re-usability. I'm working on an application (ASP.Net, C#) that has distinctly generic chunks of functionality, that I'd love to be able to lift out, all layers, into re-usable components. This means the module handles the database schema, data access, API, everything so that the next time I want to use it I can just register the module and hook into it. Developing modules of re-usable functionality is a no-brainer, but what is really confusing me is what to do when it comes to handling a core re-usable database schema that serves the module's functionality. In an ideal world, I would register a module and it would ensure that the associated database schema exists in the DB. I would code on the assumption that the tables exist, calling the module's functionality through the DLL, agnostic of the database layer. Kind of like Enterprise Library's Caching/Logging Application Block, which can create a DB schema in the target DB to use as a data store. My Questions is: What do you think is the best way to achieve this, firstly, in terms design architecture, and secondly solution structure. What patterns/frameworks do you know that exist & support this kind of thing? My thoughts so far: I mostly use Entity Framework and SQL Server DB Projects. I thought about a 'black box' approach to modules of functionality. I could use use a code-first approach in EF4, and use the ObjectContext to create a database when the module is initialized. However this means that all of the entities that my module encapsulates would be disconnected from the rest of the application because they belonged to an abstracted ObjectContext. Further - Creating appropriate indexes and references between domain entities and the module's entities would be impossible to do practically. I've thought of adopting Enterprise Library and creating my own Application Blocks. I'm not sure how this would play nice with Entity Framework (if at all) though. I like the idea of building on proven patterns & practices to encapsulate established, reusable functionality. I thought of abandoning Entity Framework for the Module, and just creating a separate DB schema for the module with its own set of stored procedures & ADO.Net. Then deploying the script at run-time if interrogation shows that it doesn't exist. But once again, for application developing outside of the application, I would want to use Entity Framework and I would have to use the module separately, disconnected from the domain ObjectContext. Has anyone had experience developing these sorts of full-stack modules? What advice can you offer? Am I biting off more than I can chew?

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  • How can I convince my company to move to MVC?

    - by guanome
    I currently write web apps using asp.net web forms and getting my company to move to another technology is like [insert funny line here]. I would really like to start writing apps using MVC, but they fear any type of change. How is the best way to convince/ease them into using MVC? I guess this can go for moving to any new technology. Update Decided to go the rogue developer route and just started using it. I recreated a small app in MVC and learned the ropes that way, and moved up from there.

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  • Description of the ASP.NET update for the .NET Framework 3.5 Service Pack 1 and the .NET Framework 2

    976765 ... Description of the ASP.NET update for the .NET Framework 3.5 Service Pack 1 and the .NET Framework 2.0 Service Pack 2 on Windows XP and on Windows Server 2003: June 8, 2010This RSS feed provided by kbAlerz.com.Visit kbAlertz.com to subscribe. It's 100% free and you'll be able to recieve e-mail or RSS updates for the technologies you pick from the Microsoft Knowledge Base....Did you know that DotNetSlackers also publishes .net articles written by top known .net Authors? We already have over 80 articles in several categories including Silverlight. Take a look: here.

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  • ASP.NET Image to PDF with VB.Net

    This tutorial will discuss how to use the PDFSharp library on images. Specifically it will cover how to do simple JPG to PDF conversion using PDFSharp in VB.NET. This has a lot of applications in ASP.NET implementations such as converting a document online that contains either a pure image or both text and images.... Comcast? Business Class - Official Site Learn About Comcast Small Business Services. Best in Phone, TV & Internet.

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  • How do I Export to excel on aspx page?

    - by meltdownmonk
    I am trying to take data that I request from an access database and put it into and excel file on the client computer. I usually use ajax to request a summary of the data I need. It is formatted into an html table. I need that table to be in an excel format for the user to download. What I have tried already is to use the vb.net code to open excel and silently save the data to a file, however I realized it's the sever side that opens excel, not the client side, in my locally testing of the code, excel would open on my machine and create the file. When running this on the network, I realized excel isn't on the server, I am not sure if I should just install it, or try and steam the file.

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  • What ASP.NET MVC Route controls the appearance of hashes in URIs?

    - by rasx
    I have integrated a Silverlight Navigation Application in an ASP.NET MVC web. However when Silverlight calls for its default page, say, IndexPage ASP.NET MVC displays the route as: http://localhost/#/IndexPage I have tried to get ASP.NET MVC to respond to this route: http://localhost/#IndexPage but I am unable to find a configuration that works with this. Does ASP.NET MVC routes respond to hashes in general?

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  • REST for ASP.NET MVC included in MVC 2?

    - by Mike Hodnick
    Are the REST for ASP.NET MVC bits automatically included with MVC 2, or do you need to download/install/use the REST for ASP.NET MVC bits separately? Specifically, I'm referring to the REST for ASP.NET MVC download here: http://aspnet.codeplex.com/releases/view/24471#DownloadId=79561 I want to use REST for ASP.NET MVC for the automatic json/xml serialization based on the incoming request's accepted content type. I'm not really finding any info about MVC2's ability to do this out of the "box".

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  • ASP.NET Application Level vs. Session Level and Global.asax...confused

    - by contactmatt
    The following text is from the book I'm reading, 'MCTS Self-Paced Training Kit (Exam 70-515) Web Applications Development with ASP.NET 4". It gives the rundown of the Application Life Cycle. A user first makes a request for a page in your site. The request is routed to the processing pipeline, which forwards it to the ASP.NET runtime. The ASP.NET runtime creates an instance of the ApplicationManager class; this class instance represents the .NET framework domain that will be used to execute requests for your application. An application domain isolates global variables from other applications and allows each application to load and unload separately, as required. After the application domain has been created, an instance of the HostingEnvironment class is created. This class provides access to items inside the hosting environment, such as directory folders. ASP.NET creates instances of the core objects that will be used to process the request. This includes HttpContext, HttpRequest, and HttpResponse objects. ASP.NET creates an instance of the HttpApplication class (or an instance is reused). This class is also the base class for a site’s Global.asax file. You can use this class to trap events that happen when your application starts or stops. When ASP.NET creates an instance of HttpApplication, it also creates the modules configured for the application, such as the SessionStateModule. Finally, ASP.NET processes request through the HttpApplication pipleline. This pipeline also includes a set of events for validating requests, mapping URLs, accessing the cache, and more. The book then demonstrated an example of using the Global.asax file: <script runat="server"> void Application_Start(object sender, EventArgs e) { Application["UsersOnline"] = 0; } void Session_Start(object sender, EventArgs e) { Application.Lock(); Application["UsersOnline"] = (int)Application["UsersOnline"] + 1; Application.UnLock(); } void Session_End(object sender, EventArgs e) { Application.Lock(); Application["UsersOnline"] = (int)Application["UsersOnline"] - 1; Application.UnLock(); } </script> When does an application start? Whats the difference between session and application level? I'm rather confused on how this is managed. I thought that Application level classes "sat on top of" an AppDomain object, and the AppDomain contained information specific to that Session for that user. Could someone please explain how IIS manages Applicaiton level classes, and how an HttpApplication class sits under an AppDomain? Anything is appreciated.

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  • Entity Framework VS LINQ to SQL VS ADO.NET with stored procedures?

    - by BritishDeveloper
    How would you rate each of them in terms of: Performance Speed of development Neat, intuitive, maintainable code Flexibility Overall I like my SQL and so have always been a die-hard fan of ADO.NET and stored procedures but I recently had a play with Linq to SQL and was blown away by how quickly I was writing out my DataAccess layer and have decided to spend some time really understanding either Linq to SQL or EF... or neither? I just want to check, that there isn't a great flaw in any of these technologies that would render my research time useless. E.g. performance is terrible, it's cool for simple apps but can only take you so far

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  • Can I create a transaction using ADO NET Entity Data Model?

    - by Junior Mayhé
    Hi is it possible on the following try-catch to execute a set of statements as a transaction using ADO NET Entity Data Model? [ValidateInput(false)] [AcceptVerbs(HttpVerbs.Post)] public ActionResult Create(Customer c) { try { c.Created = DateTime.Now; c.Active = true; c.FullName = Request.Form["FirstName"]; db.AddToCustomer(c); db.SaveChanges(); Log log = new Log();//another entity model object log.Created = DateTime.Now; log.Message = string.Format(@"A new customer was created with customerID {0}", c.CustomerID); db.AddToLog(log); db.SaveChanges(); return RedirectToAction("CreateSuccess", "Customer"); } catch { return View(); } } Any thoughts would be very appreciated.

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  • Access as a front-end to SQL Server - ADO vs DAO?

    - by webworm
    I have a project that will be using Access 2003 as the font-end and the data being stored in SQL Server. Access will connect to SQL Server via linked tables with all the database logic (stored procedures, views) within SQL Server. Given this setup, would it be better to use ADO or DAO within Access? Is it just a matter of preference or is one more suited to Access as a font-end and SQL Server as the data store? Especially when using linked tables. Thanks.

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  • How to implement nested SQL transactions with ADO.NET?

    - by manza_jurjur
    I need to implement nested transactions in .NET using ADO.NET. The situation is as follows: --> Start Process (Begin Transaction) --> Begin Transaction for step 1 --> Step 1 --> Commit transaction for step 1 --> Begin transaction for step 2 --> Step 2 --> Rollback transaction for step 2 --> etc ... --> End Process (Commit or Rollback ALL commited steps) Can that be done with transaction scopes? Could anyone post an example? In addition I'd need the prcoess to work for SQL Server 2005 AND Oracle 10g databases... will transaction scopes work with both database engines?

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  • code metrics for .net code

    - by user20358
    While the code metrics tool gives a pretty good analysis of the code being analyzed, I was wondering if there was any such benchmark on acceptable standards for the following as well: Maximum number of types per assembly Maximum number of such types that can be accessible Maximum number of parameters per method Acceptable RFC count Acceptable Afferent coupling count Acceptable Efferent coupling count Any other metrics to judge the quality of .Net code by? Thanks for your time.

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